1. Field of the Invention
The present invention relates to a plasma display apparatus that reduces the occupying area of the driving boards on a chassis base thereof.
2. Description of the Related Art
A plasma display panel (PDP) is a display device that uses plasma generated by gas discharge to produce an image thereon and has dozens to hundreds of millions of pixels (discharge cells) arranged in matrix depending on the screen size thereof. The PDP is classified into a direct current (DC) type and an alternating current (AC) type with respect to the waveform of the driving voltage and the structure of the discharge cell.
In the case of the DC PDP, the electrodes are exposed to the discharge space, and the current flows through the discharge space while the voltage is applied. Therefore, the DC PDP has the shortcoming of making a resistance to restrict the current. On the other hand, the AC PDP has a dielectric layer covering the electrodes so that the current is restricted by a capacitance formed naturally and the electrodes are protected from the ion bombardment during the discharge. Therefore, the AC PDP has the advantage of a long life over the DC PDP.
FIG. 1 is a partial perspective view of a plasma display panel. The PDP includes a first substrate 1 and a second substrate 2, the first substrate 1 and the second substrate 2 facing each other. On the first substrate 1, a plurality of paired scan and sustain electrodes 3a, 3b are formed in parallel with each other. Both the scan electrodes 3a and the sustain electrodes 3b are covered by a dielectric layer 4 and a protective layer 5 in turn. A plurality of address electrodes 6 are formed on the second substrate 2 and covered by a dielectric layer 7. Barrier ribs 8 are formed on the dielectric layer 7 between the address electrodes 6. Also, phosphors 9 are formed on the dielectric layer 7 and both sidewalls of the barrier ribs 8. The first and the second substrates 1, 2 are positioned and apart from each other by discharge space 11 in such a way that the direction of the scan and sustain electrodes 3a, 3b cross the direction of the address electrodes 6. Discharge cells 12 are formed in the discharge space 11 at the intersections between the address electrodes 6 and the paired scan electrodes 3a and sustain electrodes 3b. 
In the AC PDP, a single frame is generally divided into and driven by plural subfields, each subfield consisting of a reset period, an address period and a sustain period. The reset period is a period when the state of each discharge cell 12 is initialized to carry out addressing in the discharge cell 12 effectively. The address period is a period when the discharge cell to be turned on is selected from the discharge cells of the PDP and wall charges are accumulated in the selected discharge cell to be tuned on (the discharge cell addressed). The sustain period is a period when discharge occurs in the discharge cell to be tuned on for producing an image.
For these operations, sustain pulses are alternatingly applied to the scan electrode and the sustain electrode during the sustain period, and a reset waveform and a scan waveform are applied to the scan electrode during the reset and the address period, respectively. Therefore, it is necessary to have both a scan driving board for driving the scan electrode and a separate sustain driving board for driving the sustain electrode. Two separate driving boards need a large area for installation on the chassis base, and the cost rises due to two driving boards.
Therefore, it has been proposed that two driving boards be integrated into a single board. The single board would be placed at one end of the scan electrode and connected to the sustain electrode by extending one end of the sustain electrode. However, such an integrated driving board has the disadvantage of large impedance due to very elongated sustain electrodes.